----Does he have a soccer?
---No, he . [ ]
A. do
B. does
C. don't
D. doesn't
答案:D
塔吊的起升高度是指塔臂至地面的垂直净距离。
钻孔变径时,要先加导向,轻压钻进3~5m后方可将导向去掉。